Familial progressive myoclonic epilepsy. A clinical, genetical, biochemical and patho-anatomical study of a family with a 6-year follow-up.

Six siblings, including 4 cases of myoclonic epilepsy, their parents and 2 grandmothers were subjected to systematic investigation, and the patients were followed-up. The genetic studies revealed in the mother's family a patient with Lafora bodies demonstrated at autopsy. No chromosome abnormalities were found nor any linkage to the HLA system. The affected family members were characterized biochemically by an increased excretion of total glycosaminoglycans and/or an abnormal electrophoretic pattern of urinary glycosaminoglycans with an increased proportion of low-sulfated glycosaminoglycans. In the healthy family members this pattern of electrophoresis could also be demonstrated in the father and the paternal grandmother. Based on the biochemical results and the genetic studies it is suggested that the family members with progressive familial myoclonic epilepsy present a combination of at least 2 hereditary defects. The course of the disease has been relatively benign and treatment with sodium valproate, baclofen and clonazepam has shown quite satisfying results. In consequence of the biochemical findings combined treatment with A and E vitamins has been initiated.